A study of video buffering mechanisms and playing speed tuning techniques

Video live broadcast quality deeply depends on network bandwidth status; however, network congestion can easily occur under wireless network or mobile Internet environments, which may cause network bandwidth unstable, thereby lower video presentation quality with frequent stutters. Video buffering mechanisms are often used to ensure visual continuity and fluency; however, too much buffering time can add picture delay which cannot be stood for real-time video presentation, while insufficient buffering time cannot guarantee video presentation quality. Due to uncertain and changeable network traffic status, there is no appropriate buffering time could be used. In this paper, we proposed a dynamic adaptive video buffering mechanism, which can minimize picture delay while keeping video presentation quality. While receiving video frames as soon as possible and putting them into video buffer queue, we tune video playing speed in the form of uniformly accelerated motion by judging video frames count in video buffer queue. For tuning video playing speed in the form of sinusoidal waveform, its process is similar. They all need to update the PTS (presentation timestamp) of video frames according to the video playing speed. Related derivation process is given in detail. The calculated results show that it can absorb some network jitter.